A conventional electronic keyboard musical instrument includes a main system computer having a main system bus formed with data, address and control conductors, a main memory and a microprocessor, and at least one tone generating module. Each tone module generates a tone signal of one tone by combining, in a point-like fashion, digital values stored in a memory. Such digital values are stored in the main system data memory in the form of a table or are generated on the basis of a computation by the main system computer. Any modification of the input data leads practically immediately to a change of the contents of the memory and hence to an alteration of the tone signal. However, if several tones are present, the data memory is very large and the operating speed of the microprocessor is not sufficient to generate all of the tones needed to satisfy the acoustical requirements.